Recipe 10.4 Adding Drop-Down Menus to Coolbars 10.4.1 Problem You want to add drop-down menus to coolbars. 10.4.2 Solution Create your own menus, catch the coolbar events you want to handle, and display the menus using the Menu class's setLocation and setVisible methods .  | This is the same way context menus are created in SWT. | |
10.4.3 Discussion If you give a coolbar item the style SWT.DROP_DOWN , it'll display a chevron button , also called an arrow button , when the full item can't be displayed. Clicking that button can display a drop-down menu with all the buttons in the coolbar itemif you know what you're doing. As an example, we'll add a drop-down menu to the coolbar developed in the previous recipe. To make that menu active, we'll catch arrow button clicks (event.detail == SWT.ARROW) in the coolbar with this code in the class CoolBarListener : class CoolBarListener extends SelectionAdapter { public void widgetSelected(SelectionEvent event) { if (event.detail == SWT.ARROW) { . . . } } }
The objective here is to display the button captions as menu items, so we start by getting a list of buttons from the toolbar that was clicked: class CoolBarListener extends SelectionAdapter { public void widgetSelected(SelectionEvent event) { if (event.detail == SWT.ARROW) { ToolBar toolBar = (ToolBar) ((CoolItem) event.widget).getControl( ); ToolItem[] buttons = toolBar.getItems( ); . . . } } }
Next we create a menu with items corresponding to the button captions: class CoolBarListener extends SelectionAdapter { public void widgetSelected(SelectionEvent event) { if (event.detail == SWT.ARROW) { ToolBar toolBar = (ToolBar) ((CoolItem) event.widget).getControl( ); ToolItem[] buttons = toolBar.getItems( ); if (menu != null) { menu.dispose( ); } menu = new Menu(coolBar); for (int loopIndex = 0; loopIndex < buttons.length; loopIndex++) { MenuItem menuItem = new MenuItem(menu, SWT.PUSH); menuItem.setText(buttons[loopIndex].getText( )); } . . . } } }
Finally, we determine where the coolbar was clicked using the SelectionEvent class's x and y members and display the menu at that location using the Menu class's setLocation and setVisible methods: class CoolBarListener extends SelectionAdapter { public void widgetSelected(SelectionEvent event) { if (event.detail == SWT.ARROW) { ToolBar toolBar = (ToolBar) ((CoolItem) event.widget).getControl( ); ToolItem[] buttons = toolBar.getItems( ); if (menu != null) { menu.dispose( ); } menu = new Menu(coolBar); for (int loopIndex = 0; loopIndex < buttons.length; loopIndex++) { MenuItem menuItem = new MenuItem(menu, SWT.PUSH); menuItem.setText(buttons[loopIndex].getText( )); } Point menuPoint = coolBar.toDisplay(new Point(event.x , event.y)); menu.setLocation(menuPoint.x, menuPoint.y); menu.setVisible(true); } } }
You can see this new listener class, CoolBarListener , in the final code for CoolBarApp in Example 10-2. Note also that we add objects of this class to the two coolbar items as listeners in the code. Example 10-2. Using SWT coolbars package org.cookbook.ch10; import org.eclipse.swt.*; import org.eclipse.swt.events.*; import org.eclipse.swt.layout.*; import org.eclipse.swt.widgets.*; import org.eclipse.swt.graphics.*; public class CoolBarClass { static Display display; static Shell shell; static CoolBar coolBar; static Menu menu = null; public static void main(String[] args) { display = new Display( ); shell = new Shell(display); shell.setLayout(new GridLayout( )); shell.setText("CoolBar Example"); shell.setSize(600, 200); coolBar = new CoolBar(shell, SWT.BORDER SWT.FLAT); coolBar.setLayoutData(new GridData(GridData.FILL_BOTH)); ToolBar toolBar1 = new ToolBar(coolBar, SWT.FLAT); for (int loopIndex = 0; loopIndex < 5; loopIndex++) { ToolItem toolItem = new ToolItem(toolBar1, SWT.PUSH); toolItem.setText("Button " + loopIndex); } ToolBar toolBar2 = new ToolBar(coolBar, SWT.FLAT SWT.WRAP); for (int loopIndex = 5; loopIndex < 10; loopIndex++) { ToolItem toolItem = new ToolItem(toolBar2, SWT.PUSH); toolItem.setText("Button " + loopIndex); } CoolItem coolItem1 = new CoolItem(coolBar, SWT.DROP_DOWN); coolItem1.setControl(toolBar1); CoolItem coolItem2 = new CoolItem(coolBar, SWT.DROP_DOWN); coolItem2.setControl(toolBar2); Point toolBar1Size = toolBar1.computeSize(SWT.DEFAULT, SWT.DEFAULT); Point coolBar1Size = coolItem1.computeSize(toolBar1Size.x, toolBar1Size.y); coolItem1.setSize(coolBar1Size); Point toolBar2Size = toolBar2.computeSize(SWT.DEFAULT, SWT.DEFAULT); Point coolBar2Size = coolItem1.computeSize(toolBar2Size.x, toolBar2Size.y); coolItem2.setSize(coolBar2Size); class CoolBarListener extends SelectionAdapter { public void widgetSelected(SelectionEvent event) { if (event.detail == SWT.ARROW) { ToolBar toolBar = (ToolBar) ((CoolItem) event.widget).getControl( ); ToolItem[] buttons = toolBar.getItems( ); if (menu != null) { menu.dispose( ); } menu = new Menu(coolBar); for (int loopIndex = 0; loopIndex < buttons.length; loopIndex++) { MenuItem menuItem = new MenuItem(menu, SWT.PUSH); menuItem.setText(buttons[loopIndex].getText( )); } Point menuPoint = coolBar.toDisplay(new Point(event.x, event.y)); menu.setLocation(menuPoint.x, menuPoint.y); menu.setVisible(true); } } } coolItem1.addSelectionListener(new CoolBarListener( )); coolItem2.addSelectionListener(new CoolBarListener( )); shell.open( ); while (!shell.isDisposed( )) { if (!display.readAndDispatch( )) display.sleep( ); } display.dispose( ); } }
The results appear in Figure 10-3; clicking the chevron button that appears when you resize the coolbar items to partially obscure the first item displays the drop-down menu you see in the figure. Not bad! Figure 10-3. Adding a drop-down menu to a coolbar 
10.4.4 See Also Recipe 10.2 on creating SWT coolbars; Recipe 10.3 on adding items to coolbars. | 